In this work, we have used an oligomer model compound approach for the understanding of the vibrational spectra of the principal forms of polyaniline. Selected model compounds have been studied by Raman and infrared (IR) spectroscopies. The observed vibrational bands are assigned to the expected modes, by revealing the relationships between molecules. In a more theoretical part, dynamical calculations on the different model compounds and their related polymers are presented. The use of model compounds allows us to reach better sets of force constants, as soon as we assume that the parameters can be transferred to the polymeric forms. The obtained values of these force constants are discussed in regards to the oxidation state of polyaniline and its corresponding geometrical structure.